Human Dignity and Bioethics

40 | Daniel C. Dennett
The Problem
Human life, tradition says, is infinitely valuable, and even sacred:
not to be tampered with, not to be subjected to “unnatural” procedures,
and of course not to be terminated deliberately, except (perhaps)
in special cases such as capital punishment or in the waging
of a just war: “Thou shalt not kill.” Human life, science says, is a
complex phenomenon admitting of countless degrees and variations,
not markedly different from animal life or plant life or bacterial life
in most regards, and amenable to countless varieties of extensions,
redirections, divisions, and terminations. The questions of when (human)
life begins and ends, and of which possible variants “count” as
(sacred) human lives in the first place are, according to science, more
like the question of the area of a mountain than of its altitude above
sea level: it all depends on what can only be conventional definitions
of the boundary conditions. Science promises—or threatens—to replace
the traditional absolutes about the conditions of human life
with a host of relativistic complications and the denial of any sharp
boundaries on which to hang tradition.
Plato spoke of seeking the universals that “carve Nature at its
joints,”* and science has given us wonderful taxonomies that do just
that. It has identified electrons and protons (which have the mass of
1,836 electrons and a positive charge), distinguished the chemical
elements from each other, and articulated and largely confirmed a
Tree of Life that shows why “creature with a backbone” carves Nature
better than “creature with wings.” But the crisp, logical boundaries
that science gives us don’t include any joints where tradition demands
them. In particular, there is no moment of ensoulment to be
discovered in the breathtakingly complicated processes that ensue after
sperm meets egg and they begin producing an embryo (or maybe
twins or triplets—when do they get their individual souls?), and there
is no moment at which the soul leaves the body and human life ends.
Moreover, the more we understand, scientifically, about these complexities,
the more practical it becomes, technologically, to exploit
them in entirely novel ways for which tradition is utterly unprepared:
in vitro fertilization and cloning, organ harvest and transplant, and,
* Phaedrus 265d-266a.